-LRB- CNN -RRB- -- When I won the reality show competition `` Survivor : Africa '' in 2001 , I never dreamed that an obscure African flower would provide the drug that later helped me survive cancer . But that 's the way my life has unfolded .

One day I was battling opponents for a million dollars , the next I was battling lymphoma for my life .

I could n't have won either fight without having nature on my side . Now I 'm working hard to protect natural areas that will provide the source of future drugs that could save millions of lives .

On the show we were expected to live off the land . I learned very early that survival would mean figuring out how to work with , rather than against , nature .

We used thorny acacia plants to keep predators away from our camp . We drank from the same watering hole as elephants and giraffes , learning the best times to drink and how to stay out of their way .

Nature was a good teacher . I won $ 1 million and the confidence that I could survive just about any challenge .

In 2009 , I was diagnosed with Hodgkin 's lymphoma , and it turned out that the confidence I gained on `` Survivor '' proved even more valuable than the million dollars . But not even the trials of the show could have prepared me for the greatest struggle of my life .

Chemotherapy drugs wracked my body for months . But as they worked I found some comfort when I learned that one of them was derived from an African flower , the rosy periwinkle .

The drug born of this flower , vincristine , was part of the regimen that saved my life . My cancer is now in remission and once again I owe my survival to working with nature .

My case is not an isolated one . It turns out that dozens of plants in nature manufacture anti-cancer agents as chemical defenses . Scientists figured this out years ago , and 80 percent of all anti-cancer drugs possess an active ingredient from the natural world .

This promise extends to other diseases as well , with half the new drugs created in the past 25 years derived from nature .

According to a recent study , natural drugs and related products are used to treat 87 percent of all known diseases , including cancer , heart disease , diabetes and HIV .

Yet this pharmaceutical pipeline is in danger .

Researchers unraveled the biochemistry of the snakeroot plant to improve the treatment of hypertension , but the plant is now threatened by deforestation in Indonesia .

Scientists derived a compound for treating severe chronic pain from a cone snail found in Pacific coral reefs , though its habitat is now threatened by destructive fishing practices and marine pollution .

The first antiviral medication approved for the treatment of HIV/AIDS came from a marine sponge , yet marine habitats around the world are threatened by pollution , overfishing and climate change .

Given the accelerating destruction of rainforests , reefs and other natural habitats around the world , we must take action today -- as there 's no telling how many useful undiscovered natural compounds we could lose for tomorrow .

Right now , there 's a bipartisan bill in Congress , the Global Conservation Act of 2010 , that seeks to address extinction and natural resource depletion worldwide by laying out a strategy for helping other countries protect millions of square miles of natural habitat .

President Obama must put his weight behind this bill and the Congress must pass it soon .

According to the World Conservation Union , more than 16,000 species , plant and animal alike , are in danger of extinction , largely because of human activities .

Indeed , scientists warn that two-thirds of the planet 's 10 million species could face extinction by the end of the century . Time is not on our side .

I won `` Survivor : Africa , '' and I 've won my battle against cancer . But in each case , I did n't do it alone . I had the most unlikely of partners : a small watering hole and , later , a flower .

I do n't know what I 'll need from nature next or where the newest nature-based medicines will come from , but I 'm not willing to risk losing any of them .

The rosy periwinkle saved my life . Who knows what could save yours ?

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Winner of TV 's `` Survivor : Africa '' beat cancer with chemo from African plant

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Ethan Zohn 's brush with death spurred him to save natural habitats

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Zohn urges Congress to pass bill that outlines strategy to protect natural habitats